This invention generally relates to a disk brake assembly and specifically to a self-energized disk brake assembly including features for stabilizing braking force gain.
Conventional disk brake assemblies require a considerable amount of mechanical force to obtain the required braking force. The mechanical force is typically provided by a hydraulic piston actuated to force brake pads against a rotor. The piston is typically movable within a caliper housing. The caliper housing is either of a fixed or floating configuration. A fixed caliper housing remains fixed relative to the rotor as the brake pads move into contact with the rotor. A fixed caliper includes two pistons for moving the brake pads into engagement with the rotor. A floating caliper uses a single piston that moves one of the brake pads into contact with the rotor, and floats to pull the second pad into contact on an opposite side of the rotor.
A Self-energizing brake creates additional braking forces above any applied force to increase braking forces on the rotating brake member. Self-energizing brakes are known in the art, and have several problems that have so far prevented wide spread use in motor vehicles. The multiplication of braking force is generated by a specific configuration of brake pad or shoe and a frictional force caused during engagement with the rotating brake member. An applied force causes engagement between the rotating brake member and the brake pad. Rotation of the rotating brake member pulls the brake pad or shoe into the rotor, multiplying the overall braking force.
Disadvantageously, inconsistencies in frictional force and applied force between different wheels of a vehicle result in disproportionate amounts of braking force applied to each wheel. Non-uniform braking pressure on each wheel can result in undesirable vehicle handling. Further, the amount of applied force is not linearly proportional to the increase in braking force caused by self-energization. The result of such a non-linear relationship is large variations in braking force increases that are not controllable or consistent.
Accordingly, it is desirable to develop and design a self-energizing brake assembly having a stable, uniform and predictable gain in braking force.